article: Snack time is a part of the day for children of all ages. But new research suggests that kids snacking in big groups could be at risk for _ .
  Scientists from American University looked at the eating behavior of 54 kids between the ages of 2 and 6. At snack time, the scientist watched the amount of food each child ate while they were in groups of either three or nine. According to the study, the more children there are in a group, the more likely they are to eat more. Those in the larger group ate nearly 30 percent more than those in the smaller group, and they actually ate faster.
  Since this is the first such study in children, scientists are quick to point out the importance of encouraging healthy habits in kids as early as possible.
  "If you know kids eat more in large groups, it seems perfect to use this information to keep snack groups small or use small tables," says Dr. Jana Klauer, an expert in New York.
  Smaller groups would allow for a quiet and more relaxing environment-a perfect chance to teach children about food, manners and how to know when they feel full. "This would have an effect on kids' eating," adds Klauer. "They would slow down and eat less."
question: How many times have the scientists done such study according to the passage?
options: Once Twice Three times Many times